The general syntax of the grep commands is: You can use fgrep to find all the lines of a file that contain a particular word. For example, to list all the lines of a file named myfile in the current directory that contain the word dog, enter at the Unix prompt:
Outer core. The outer core of the Earth is a liquid layer about 2,300 km (1,400 mi) thick and composed of iron and nickel that lies above Earth's solid inner core and below its mantle.Its outer boundary lies 2,890 km (1,800 mi) beneath Earth's surface.ecause of its high temperature, modeling work has shown that the outer core is a low viscosity fluid (about ten times the viscosity of liquid metals at the surface) that convects turbulently. Eddy currents in the nickel iron fluid of the outer core are believed to influence the Earth's magnetic field.
The Core's Gross Shape. We knew by the 1890s, from the way Earth responds to the gravity of the Sun and Moon, that the planet has a dense core, probably iron. In 1906 Richard Dixon Oldham found that earthquake waves move through the Earth's center much slower than they do through the mantle around itâbecause the center is liquid. In 1936 Inge Lehmann reported that something reflects seismic waves from within the core. It became clear that the core consists of a thick shell of liquid ironâthe outer coreâwith a smaller, solid inner core at its center. It's solid because at that depth the high pressure overcomes the effect of high temperature.